1. Field of the Invention
The present invention relates to a video communication system for exchanging video information, audio information, and data between a plurality of terminal units.
2. Related Background Art
As conventional systems for exchanging video information, audio information, and data between a plurality of terminal units, a video phone system, a video conference system, and the like are available.
For example, the conventional video conference system includes a room type system, a roll-about type system, and a desktop type, which are selectively used in accordance with application purposes.
In the conventional room type video conference system, participants in a video conference take seats around a predetermined conference table in a conference room to face a video camera so as to allow the video camera to photograph the participants. At the same time, voices from the respective participants are picked up by a nondirectional microphone which is placed on the conference table to pick up voices from all the participants. In addition, a monitor apparatus for displaying a photographed image taken in a conference room of the other party and sent therefrom is placed in the conference room at a position where the participants seating at the conference table can see (e.g., on a wall).
The above video camera has a so-called zoom function. The video camera is also placed on an automatic panhead which can be operated by remote control with a control console or the like. The video camera on the automatic panhead can be panned or tilted by operating the control console to photograph some of the participants in close-up.
Room type video conference systems similar to the above system are installed for two parties to hold a many-to-many video conference in which a plurality of participants exchange information with a plurality of participants.
The roll-about video conference system is different from the above room type system in that a monitor apparatus smaller in size than the monitor apparatus placed on the wall is placed on, e.g., a cart with castors to be conveyed. In addition to the compact monitor apparatus, equipment required for a video conference, e.g., a video camera, a microphone, a coding/decoding device (to be referred to as a codec hereinafter), and a communication line interface (I/F) are stored in the above cart.
If each party carries a roll-about type video conference system like the one described above into a general conference room, many-to-many video conference can be easily held without preparing dedicated conference rooms in each of which the above room type conference system is installed.
The desktop type video conference system includes a personal computer (to be referred to as a PC hereinafter), a display monitor apparatus for the PC, a keyboard and a mouse for PC input operations, a video camera with a manual panhead, a desk microphone, and the like. An expansion board having a codec and a communication line I/F is mounted in an expansion slot of the PC body. In this system, software for a video conference is executed on the PC to operate the system. With this operation, a video conference can be held.
In the above desktop video conference system, the system is operated by using the keyboard or the mouse for PC input operations. A moving image sent from the other party is displayed by using a display monitor apparatus for the PC instead of using a special monitor apparatus. The image is displayed on the display screen of the monitor apparatus in a window display (overlay) scheme.
If the other party also uses a desktop type video conference system similar to the above system, a one-to-one video conference can be held while both the participants are sitting on seats. If the other party uses a room type conference system or a roll-about type video conference system, a one-to-many video conference can be held while the participants are sitting on seats.
The above conventional video conference systems have the following drawbacks.
When the room or roll-about type video conference system is to be used, since a conference room is indispensable for the system, various preparations, e.g., reservation of a conference room, movement to the conference room, and carrying of references into the conference room, must be made before a video conference. These preparations cause time losses and require cumbersome operations.
When the desktop type conference system is to be used, since a conference can be held, without using any conference room, while each participant is sitting on a seat, the above preparations, e.g., reservation of a conference room, movement to the conference room, and carrying of references into the conference room, need not be made before a video conference. This system is free from the time losses and the cumbersome operations accompanying the various preparations. If, however, both parties use desktop type video conference systems, only a one-to-one video conference can be held. If a one-to-many video conference is to be held, the party of many participants must use the above room or roll-about video conference system and hence must use a conference room. The problems of time losses and cumbersome operations remain unsolved.
If a plurality of room or roll-about type video conference systems installed at multiple points are connected to each other through multipoint control units (to be referred to as MCUs hereinafter), a multipoint video conference can be held. In this case as well, since conference rooms must be used, the above problems cannot be solved. If a plurality of desktop video conference systems installed at multiple points are connected to each other through the above MCUs, an on-seat type multipoint video conference can be held by people at the multiple points. The MCU itself is an expensive device. In addition, lines to be connected are required in number equal to the number of participants in the video conference. For this reason, the charges for lines are high.